7500Vpk isolation in a field-swappable gull-wing package
The onsemi H11A5FM is a single-channel optocoupler with a DC input and a phototransistor output that brings out the base pin — handy if you need to bias the transistor for faster switching or tailor the gain with an external resistor. The headline number here is the 7500Vpk isolation voltage, which puts it in the class for industrial equipment where you need a solid creepage barrier between a 24V control side and a higher-voltage load side, or across a noisy motor drive bus. It comes in a 6-SMD gull-wing package (6-SMD supplier device package), so it sits flat on the board and the leads are visible for inspection after reflow — a detail that matters when you are doing a quick visual check on a rework bench or in a field repair where you do not have an X-ray machine.
Switching speed and drive requirements for logic interfacing
Typical turn-on and turn-off times are 2 µs each, which means this part comfortably handles 100 kHz data rates for things like PLC digital input isolation or gate-drive feedback where you are not pushing past a few tens of kilohertz. The 30% minimum current transfer ratio at 10 mA forward current guarantees the output transistor pulls hard enough to saturate a downstream logic input — you do not need to overdrive the LED to get a clean logic level. Forward voltage is 1.18 V typical, and the LED can take up to 60 mA continuous, so a 5V logic output driving through a 390-ohm resistor lands right at the 10 mA test point. The output transistor saturates at 400 mV max (Vce saturation), leaving nearly the full 30 V output rating for the load side — useful if you are switching a 24 V industrial signal rail. Operating temperature spans -40°C to 100°C, covering the industrial enclosure range without needing a heated cabinet. The base pin is brought out, so you can add a pull-down resistor to speed up turn-off or a bias network to adjust the switching threshold — a feature the three-terminal optos do not offer.
onsemi lists the H11A5FM as Obsolete. For new designs, look at current-production single-channel optocouplers in the same 6-SMD footprint from onsemi or other manufacturers that offer 7500 Vpk isolation and a transistor output with base access. The H11A5FM remains a viable repair or short-run production part as long as surplus inventory holds.